Few comprehensive, descriptive studies regarding educator use of social media for informal professional learning have been conducted. The purpose of this study was to examine, through a survey tool with both qualitative and quantitative components, educators' perceptions and reported behaviors associated with participation in informal, online professional development networks and how they differed based on current assignment, years in education, and age. It is the hope of this researcher that this baseline description expands our understanding. The study explored adult learning theories and the notion of connectivism. Combining these with an understanding of social media's role in the development of PLNs, the researcher advocates for a new paradigm of professional development that is self-directed, differentiated, job embedded, and social. Educators (n = 133) from pre-K-higher education responded to an online survey with both Likert scale items and open-ended questions. Educators designated Twitter their favorite social media application for informal professional development. Educators believe they should take personal responsibility for professional growth, and they reported that they learn how to use educational technology through informal and independent learning, even though few said that their employers encourage this type of learning. Respondents said that participating in informal professional development helped them become better educators. The study revealed a disconnect between administrators and classroom teachers regarding methods of support and the effectiveness of professional development. Several themes emerged from the open-ended responses, which were supported by the quantitative data and echoed the adult learning theory themes of "friends educating each other" and Paulo Freire's theory that learning is social. This descriptive study suggested that educators be encouraged to move fluidly between traditional, physical, and virtual networks in a transparent, newly legitimized manner in order to improve their practice and, ultimately, increase student engagement and learning. The research provides information useful to stakeholders regarding future decisions about the use of social media for informal professional development, which may be applied to other areas of professional learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]